A communication system may be a facility that enables communication between two or more nodes or devices, such as fixed or mobile communication devices. Signals can be carried on wired or wireless carriers.
An example of a cellular communication system is an architecture that is being standardized by the 3rd Generation Partnership Project (3GPP). A recent development in this field is often referred to as the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. E-UTRA (evolved UMTS Terrestrial Radio Access) is the air interface of 3GPP's Long Term Evolution (LTE) upgrade path for mobile networks. In LTE, base stations or access points (APs), which are referred to as enhanced Node AP (eNBs), provide wireless access within a coverage area or cell. In LTE, mobile devices, or mobile stations are referred to as user equipments (UE). LTE has included a number of improvements or developments. 5G (or 5th generation) wireless networks are also being developed.
In LTE, the system may include an on-demand system information (SI) delivery mechanism in which on-demand SI is transmitted to UEs. For instance, when an UE is attempting to access the network, the UE can request on-demand SI during a random access procedure. The UE receives an acknowledgment from the base station in response to the on-demand SI. Then, the base station transmits an SI message to the UE during an SI window that contains one or more parameters in the form of one or more blocks to enable the UE to communicate in the wireless network. However, the base station is not mandated to transmit SI messages when requested. For instance, the base station may be facing a congestion in the downlink channel or other transmissions are given priority over requested SI messages, and the base station may not be able to promptly transmit an SI message to the requesting UE within the next one or more SI windows. In such situations, the UE may re-attempt the SI request, which may load the random access channel (RACH) since the base station will not provide the requested SI before a certain time.
In LTE, a backoff indicator field can be signaled by the network as part of a media access control (MAC) sub-header in a random-access channel (RACH) response. With respect to a value of the backoff indicator, the UE may select a random backoff time according to a uniform distribution between 0 and the backoff parameter corresponding to the signaled backoff indicator. The backoff time is applied only if the random access response (RAR) reception is considered not successful, which occurs if none of the received RARs contain a Random Access Preamble identifier (RAPID) corresponding to the transmitted RA preamble. As such, this backoff indicator cannot be applied by the UEs that have successfully received a RAR. In this case, the UEs that have received an ACK in the RAR will attempt to decode the SI message in the next SI window, and if the SI message is not delivered, the UEs will re-send new SI requests, which may cause congestion on the network.